Photosensitive system



United States Patent PHOTOSENSITIVE SYEiTEM Lyman Cliallrley,Washington, D. C.

No Drawing. Application October 24, 1955 Serial No. 542,479

28 Claims. (CI. 96-90) The present application relates to aphotochemical process and product and, more particularly, to aphotosensitive system based on a combination of a hydrophilic dyecyanide with a hydrocolloid.

It has long been known that the triphenylmethane dyes, which aretriphenylmethane derivatives containing at least one auxochromic group,such as the amino or hydroxyl, para to the central methane carbon atom,form leuco cyanides which in the presence of certain activators becomephotosensitive to ultraviolet and shorter wave lengths of light toproduce colored compounds but which are not sensitive to light in thevisible range. Because of this property, the substances may be used inphotographic and photoduplication processes to print out images that arefully formed without development, that may be permanent and that may beexamined in ordinary interior illumination without fixing. The papersemployed retain their ultra-violet sensitivity after the printing of oneimage so that other portions may be printed on at a later date.

Aside from the photographic and photoduplication applications, thecolorless dye cyanides are particularly valuable in the recording andmeasurement of ultra-violet radiation which has generally involved theuse of expensive equipment to isolate this region, such as quartzspectrographs and photoelectric meters. Using the triphenylmethane dyecyanides, there can be prepared photosensitive papers that respond onlyto the shorter Wave ultraviolet and thus provide materials for recordingand measuring this region with the ease of a photographic printing outprocess. Suitable base papers may be impregnated with solutions of thedye cyanides in an activator to form sensitized papers which print outfully formed permanent images. Such papers may be readily prepared whichare sensitive to 3250 A. and shorter and to 3350 A. and shorter wavelengths but which are quite unaffected by sunlight passing throughcolorless glass which will screen out the lower Wave lengths of light.Thus there can be formed very inexpensive actinometers for suchspecialized purposes as measuring the short Wave and ultra-violet outputof lamps, the erythemal component of sunlight, and dosages oftherapeutic ultra-violet.

Another use for the papers is in recording instruments where a beam ofultraviolet light may be employed to trace a line which is fully Visiblebehind a window of colorless ultra-violet absorbing glass.

However, all of the known activators for the dye cyanides are organicmaterials that have an appreciable vapor pressure and tend to evaporateon exposure to air, thus materially reducing the shelf life of thephotosensitive material. Also, most of the known activators are liquidsor oily solids and since they must be present at the time of exposure toultra-violet light, they tend to cause diffusion of the image as, it isformed causing it to be less sharp and well defined. Also, theseactivators tend "ice to promote diffusion of foreign substances, whichmay be gases in the air, and which may be deleterious, into thephotosensitive composition or, on the other hand, the activator, itself,may difiuse from the composition into or onto another material withwhich it comes in intimate contact.

Accordingly, it is a primary object of the present invention to providea solid composition including a triphenylmethane dye cyanide of longshelf life which is activated by a non-volatile and solid organicmaterial so as to be sensitive to ultra-violet light.

A further object of the invention is to provide an activatedtriphenylmethane dye cyanide composition capable of printing out asharp, permanent image when subjected to ultra-violet light.

Another object of the present invention is to provide an activatedtriphenylmethane dye cyanide composition sen sitive to ultra-violetlight from which there will be no diffusion of the activator.

Still anothercbject of the invention is to provide an activatedtriphenylmethane dye cyanide composition which is readily applicable asa film on a supporting base.

Another and further object of the invention is to provide aphotochemical process which utilizes a composition which accomplishesthe foregoing objects.

Other and further objects will be apparent from the following detaileddescription of the invention.

It has been found that the hydrophilic triphenylmethane dye cyanides ofthe phenolic and amino types form photosensitive combinations withhydrocolloids. As examples of hydrocolloids which may be employed, theremay be mentioned various carbohydrate compounds in the form ofhydrocolloids such as cellulose itself (cotton textiles, paper and thelike), methyl cellulose, fl-hydroxyethyl cellulose, starch and dextrine;polyhydroxy colloids, such as sorbitol and the various polymers of vinylalcohol and partially acetylated vinyl alcohol; proteinaceous substancesbelonging to the classes of albumins and collagens such as egg albumin,gelatine and the various animal glues; and plant gums such as agar-agar,gum arabic, gum tragacanth, karaya gum, pectins and algin.

The triphenylmethane dye cyanides in which at least one hydroxy groupserves as the auxochromic group in the position para to the centralmethane carbon atom are hydrophilic in nature because of the hydrophiliccharacter of the hydroxyl group and they may contain other hydrophilicgroups, such as the sulfonic acid group. Thus dye cyanides of this typewill form photosensitive combinations with a hydrocolloid. Many of thephenolic dyes, however, sufit'er from the disadvantage that they formdeeply colored compounds only at relatively high pI-Is. However, byincluding in the photosensitive composition containing a hydrocolloid,basic compounds such as, for example, an ethanolamine or a quaternaryammonium base, which will assure the required basicity, a photosensitivecomposition which will print out sharp, clear, deeply colored images canbe obtained, although the images may not be permanent because of thetendency of the basic compound to react with acidic gases in the air.

The cyanides of the amino triphenylmethane dyes, however, fall into twogeneral classes, hydrophobic and hydrophilic dye cyanides. Thehydrophobic dye cyanides are water repellent and very little soluble inwater and they are not activated by water so as to be sensitive toultra-violet light.

An example of a hydrophobic dye cyanide in which the auxochrornic groupis an amino function is 4,4,4"-

3 tris-dimethylaminotriphenylacetonitrile, the hydrophobic dye cyanideof crystal violet, having the formula IIKCHah N(CH:)2 va- 3):

By the further addition of a hydrophilic group, such as the sulfonicacid, quaternary ammonium or hydroxyl group to the molecule, thehydrophobic dye cyanides are converted to those whichare hydrophilic incharacter without destroying their potential photosensitivity to lightin the ultra-violet and they have been found to form photosensitivecombinations with hydrocolloids.

In my copending applications, Serial Nos. 494,270, now abandoned, and494,271, now PatentNumber 2,839,- 542, both filed March 14, 1955, I havedisclosed amino triphenylmethane dye cyanides which are hydrophilic innature. In the instant application, there will be disclosed additionalexamples of such compounds along with processes for their manufacture.These hydrophilic dye cyanides, without exception, form photosensitivecombinations with the hydrocolloids.

As stated earlier, the sulfonic acid group is one of the groups whichmay be substituted in a hydrophobic amino triphenylmethane dye cyanideto render it hydrophilic. This group may be attached directly to acarbon atom of one of the benzene rings of the triphenylacetonitrilecompound and this may readily be accomplished by any of the conventionalsulfonation techniques. On the other hand, the sulfonic acid group maybe associated with one of the amino nitrogen atoms in the para positionand this last mentioned substitution may conveniently be effected by theaddition to a para-amino group of a suitable sulfonated aryl group suchas a phenyl, benzyl or naphthyl group.

The number .of sulfoni'c acidgroups in the molecule of hydrophilic dyecyanide is .not critical and there may be one or more, andthe sulfonicacid groups may be present as free sulfonic acid groups or as watersoluble salts, such as, for example, the salts of the alkali andalkaline earth metals.

When ahydroxyl group is that which imparts a hydrophilic character to anamino triphenyla'cetonitrile, it may conveniently be introduced in theform of an alkanol group attached to an amino nitrogen atom. The alkylportion of the group may bean ethyl or a propyl radical, the propylradical being either primary or secondary. The alkanol group may beintroduced by reacting the amino triphe nylacetonitrile with aconventional fi-hydroxy-alkylating agent such as an alkylenechlorohydrine or alkylene oxide.

The hydroxyl group which imparts a hydrophilic character to an aminotriphenylacetonitrile may also be a substituent on an aryl nucleus, forexample, one of the phenyl groups attached to the central methane carbonatom.

With respect to the employment of a quaternary ammonium group :as thehydrophilizing substituent, this group may conveniently be derived fromone of the para amino groups of the dye cyanide although it will beobvious that, if desired, other .means may be'employed for itsintroduction. It may be represented by the formula in which R, R and Rare each an alkyl group such as methyl, ethyl, propyl, butyl or benzyland may be the same or different and X is an anion such as a halide,sulphate, acetate, propionate, oxalate, p-toluene sulfonate, benzenesulfonate, sulfamate and perchlorate. The benzyl group listed is, ofcourse, an aryl substituted alkyl group but it behaves in most respectslike an alkyl group and may be classed therewith.

The quaternary ammonium group may conveniently be formed by the actionof conventional alkylating agents such as an alkyl halide on an aminotriphenylmethane dye cyanide.

It will be understood, of course, that more than one type of hydrophilicgroup may be present in the same molecule of dye cyanide. An example ofsuch a compound is patent blue V cyanide, the cyanide of the dye havingColour Index No. 712, which contains both sulfonic acid groups and ahydroxyl group. This dye cyanide provides an excellent photosensitivecomposition when combined with a hydrocolloid.

The method of combining the hydrophilic dye cyanide with thehydrocolloid is not critical. It is only necessary that the dye cyanide,preferably in solution, be brought into intimate contact with thehydrophilic colloid. When the colloid is in a solid state, it may be wetwith a solution of the hydrophilic dye cyanide as by immersion thereinwith the excess of solution being removed in any convenient manner andthe remaining solvent volatilized. This method is particularly suitableforthe preparation of a photosensitive product employing an absorptivecellulose sheet, such as paper or a cotton textile. The dried productwill be found to be photosensitive to ultraviolet and Roentgen rays. Thedried cellulose sheet will, after exposure, print out clear, sharpimages.

Another convenient method of forming the photosensitive combination-isto admix a solution of the hydrophilic dye cyanide with a hydrocolloidwhich is also dissolved or-dispersed in a suitable solvent. Water may beused as the solvent if the-dye cyanide is sufficiently water soluble topermit an intimate admixture with a solution of hydrocolloid. Also,various volatile organic solvents, for instance, methyl alcohol, ethylalcohol, propyl alcohol, i-propyl alcohol and acetonitrile, may be usedalone or mixed withwater, as the solventfor the hydrophilic dye cyanide.

The liquid mixture so formed may then be used to coat any suitable baseor support and preferably one having a smooth, planar surface. Asexamples of such supports may be mentioned glass, metal or plasticsheets. The volatile solvent is then driven off leaving thephotosensitive dye cyanide-hydrocolloid combination as a tightlyadherent film.

This procedure .lends itself excellently to the preparation of coatedmaterials which have a number of important uses, for example, coatedglass plates may be used for the'preparation of lantern slides and othertransparencies which can be projected or examined by visible lightwithout any fixing process and without destroying the ultra-violetphotosensitivity. Likewise, cellulose acetate and similar films may becoated to make transparent photosensitive materials.

Papers may also be coated, and, for example, Baryta coated photographicraw stock, when coated with a photosensitive film, affords an opaquephotosensitive sheet that gives ajmaximuni of contrast" and resolutionas compared with water leaf paper which is sensitized by a simplecombination with agdye cyanide alone. In general, cellulose sheetmaterials which are heavily coated or sized should be processed by thecoating technique rather than impregnated with the dye cyanide alone.For instance, if a hydrophilic dye cyanide, alone, is applied insolution to Bristol board, there 'is imparted only a light and irregularsensitization.

For the coating operations, it is generally desirable to chooseahydrocolloid-such as gelatine, polyvinyl alcohol,

to a smooth, transparent, uniform film, rather than a hydrocolloid whichdries to a rough or translucent film,

such as methylcellulose, karaya gum or carboxymethyl cellulose. Thehydrocolloid-dye cyanide combination is capable of giving films ofextremely high resolution so that images will show microscopic detail.These films have no grain like a silver emulsion, and are transparentand uniform under a microscope. The images formed have the property ofbeing as sharp as the beam of light producing the image. Where the imageis projected by a lens or other focusing device, maximum resolution isobtained by making the photosensitive film very thin so that it may beplaced at the exact focus at which the image is formed and thus hold toa minimum the sidewise difiusion of the image as the light passesthrough the film.

The relative proportion of hydrophilic dye cyanide to hydrocolloid inthe photosensitive combination is not critical and mustnecessan'ly varywidely in accordance with such factors as the nature of the dye cyanide,itself, the viscosity of the colloidal material employed in pre= paringthe combination and thethickness of the dried films. In general, theamount of dye cyanide should be kept as low as possible consonant withthe formation of clear, deeply colored images. In most instances, theproportion of hydrophilic dye cyanide will fall within the range of 0.1to 10.0% based on the weight of the photosensitive combination of thecyanide with solid hydrocolloid. I

Expressing the amount of colorless dye cyanide in terms of the exposablesurface area of the photosensitive product, whether it be a coatedproduct or one formed by treating a hydrocolloid in solid form with ahydrophilic dye cyanide, alone, it has been found that there may be from.01 to mgms. of dye cyanide per square inch of surface. A preferredrange may be given as .05 to 1.0 mgm.

The following examples in which the Colour Index Number of the parentdye is given wherever possible are set forth as being illustrative, butnot as limiting the present invention.

Example 1 0.1 gram of ethyl green cyanide having the formula Color IndexNo. 685

and prepared as disclosed in my pending U. S. application Serial No.494,271, filed March 14, 1955, is dissolved in 25 ml. of water and mixedat 50 C. with 25 ml. of a 10% aqueous solution of gelatine. The mixtureis cooled to 35 C. and poured onto level glass plates, using.

Example 2 Pure white cotton broadcloth is wet with a 1% solution ofethyl green cyanide, squeezed between rubber rollers (such as a clotheswringer) and dried in the dark. The dry cloth is exposed behind astencil to ultraviolet of wave length shorter than 3350 A. to printalgteeii design on the 'eolo'rless cloth background.

Example 3 7 Equal volumes of a 1% aqueous solution of ethyl greencyanide and a 10% aqueous solution of polyvinyl alcohol (El'vanol 72-51)are heated to C. and mixed. The solution is cooled to 18 C and coatedonto white Bristol board, which is dried in the dark. The dry coatedBristol board may be printed on by ultraviolet of wave length shorterthan 3350 A. to produce a positive image from a negative.

Example 4 Example 5 A 5% aqueous solution of agar-agar is substitutedfor the 10% corn starch solution used in Example 4 to produce aphotosensitive agar-agar pigment.

Example 6 A solution of 10 g. of white dextrine and 1 g. of ethyl greencyanide is spray dried to give a colorless photosensitive pigment thatbecomes green on exposure to ultra-violet of wavelength shorter than3350 A.

Example 7 One gram of patent blue V cyanide, having the formula ColorIndex No. 712

and prepared as disclosed in my oopending application Serial No.494,270, filed March 14, 1955, is dissolved in ml. of water. One volumeof this solution is mixed at 50 C. with 1 volume of 10% aqueous solutionof gelatine. The combined solution is used to coat glass, paper or othermaterials, which are dried in the dark to form photosensitive printingmaterials that give a strong blue image on exposure to ultra-violet.

Example 8 The sodium salt of Helvetia green cyanide having the formulaona some om com Index no. see

is prepared by adding to 35 g. of chlorosulfonic acidslowly withstirring at room temperature g. of powdered4,4-bis-dimethylamino-triphenylacetonitrile. The resulting clearsolution is heated slowly in a 250 ml. flask to 85 C. and heldat thattemperature until the vigorous evolution of gas subsides. The solutionis then heated to 100 C. for 10 minutes, cooled, poured onto 180 g. ofcracked ice, the resulting solution filtered and the filtrate treatedwith a solution of 40g. of sodium hydroxide in 750 ml. of water. 7 Theresulting mixture is allowed to stand at C. for 24 hours and theprecipitate collected on a filter and air dried. About 12 g. of crudeHelvetia green cyanide sodium salt is thus obtained. The crude productis recrystallized from 1% aqueous sodium chloride solution.

One volume of a warm (50 C.) aqueous solution of the sodium salt ofHelvetia green cyanide is mixed with one volume of a cold C.) aqueoussolution of egg albumen and the mixture used to coat Bristol board,which is dried in the dark. The coated paper prints a green image onexposure to ultra-violet,

Example 9 4,4',4-tris-di-;8 hydroxy ethylaminotriphenylacetonitrilehaving the formula 7 (JAN is prepared as follows: Five g. of 4,4',4"triamino-triphenagain refluxed for /2 hour in 100 ml. of ethylene chlorohydrine, which is then distilled off as before. The residue is taken upin water andprecipitated with sodium carbonate as before. dried.It-contains a major proportion of the compound of the'above'formula butalso some of the tetraandpenta-B-hydroxyethyl-triamino-triphenylacetonitriles.

Two tenths of a gram of 4,4,4"-tris-di-5-hydroxyethylaminotriphenylacetonitrile dissolved in ml. of 91% ipropyl alcoholis mixed at 25 C. with 1 volume of a 10% aqueous solution of methylcellulose (Methocel NF, viscosity l5 cps. grade). Glass plates arecoated with the resulting solution, using 1 ml. of solution to twosquare inches of glass surface, and the plates are dried in the dark.The colorless film is clear but reticulated, which gives a diffuseoptical eflFect desirable for some purposes. Exposure to ultra-violet ofwave lengths shorter than 3250 A. yields a bluish violet image.

Example 10 In a preparation carried out as in Example 9,fi-hydroxy-ethyl-cellulose (Cellosize WP-09) I is substituted for themethyl cellulose. The resulting film is smooth and has a high resolvingpower when printed upon.

. Example 11 The disodium salt of formyl violet S4B cyanide having theformula The final product is collected and Color Index No. 698

is prepared as follows: A solution of 25 g. of Acid Violet 4BNS Ex.Conc., the Ciba Company brand of Formyl Violet S4B, Colour Index No.698, in 350 ml. of boiling water is filtered from a slight impurity,cooled to 38 C. and treated with a solution of 2.6 g. of sodium cyanidein 15 ml. of water. The following operations are carried out by yellowlight such as the illumination from a Kodak OA safelight. The solutionis cooled to 25 C. and allowed to stand in the dark for 24 hours, duringwhich time a colorless precipitate forms. The solution is filtered fromthe precipitate, which is sucked as dry as possible on the filter andair dried to yield about 7 g. of the disodium salt of the compound.

A solution of 0.5 g. of the disodium salt offormyl violet S4B cyanide in250 ml. of water at 25 C. is mixed with 250 ml. of an aqueous 10%gelatine solution at 75 C., and glass plates are coated with thissolution, using 0.5 ml. of solution per square inch of glass plate. Ondrying in the dark the films are colorless and transparent. They givepermanent, grainless, violet images on exposure to wave lengths shorterthan about 3300 A.

Example 12 Guinea green cyanide free acid having the formula CZH5 H CzHsColor Index No. 666

is prepared as follows: A solution of 25 g. of commercial Acid Green,Ex. Conc., the Ciba Company brand of Guinea Green B, Colour Index No.666, in 250 ml. of boiling water is cooled to 40 C., filtered, andtreated in yellow light, such as the illumination from a Kodak OAsafelight, with a solution of 2 g. of 95% sodium cyanide in 15 ml. ofwater. The following operations are also carried out in yellow light.The solution is allowed to stand in the dark at 25 C. for 24 hours andthen treated in a good hood with 9 ml. of concentrated hydrochloric acidto precipitate the free acid of the dye cyanide.

After the mixture has stood for another 30 hours in the dark at 25 C.the dark brown precipitate is collected on a filter, sucked as dry aspossible, and air dried at room temperature to an amorphous mass,weighing about 14 g. This is purified by solution in 15 times its Weightof boiling water, filtration of the hot solution, cooling, standing for1 week and collection of the newly formed precipitate. 3 Thisprecipitate also is dried at room temperature.

One gram of guinea green cyanide free acid, is dissolved at roomtemperature by stirring in a mixture of 13 ml. of normal sodiumcarbonate solution and 37 ml. of water. This solution is mixed with ml.of 10% gelatine solution at 50 C. and 50 ml. of i-propyl alcohol at 9 25C. Twenty-four pound water leaf paper is impregnated by dipping in thissolution and dried in the dark. It prints a permanent green image onexposure to ultraviolet.

Example 13' Tri-fi-hydroxyethyl-p-rosaniline cyanide having the formulaandfiltered hot again from the newly formed calcium sulfate. Thefiltrate is further evaporated to '55 ml. filtered hot from calciumsulfate and the filtrate cooled and allowed to stand in the dark at C.for 24 hours. The precipitated calcium salt of acid fuchsine cyanide iscollected on a 'filter, pressed between dry filter papers to removemother liquor, and dried in vacuo over sulfuric is prepared as follows:A solution of 5 g. of 4,4',4"-triamino-triphenylacetonitrile in 100 ml.of ethylenechlorohydrine is boiled under a reflux condenser for /2 hourin yellow light, such as illumination from a Kodak 0A safelight. Thisillumination is continued through the rest of the preparation. After therefluxing, 80 to 85 ml. of the ethylenechlorohydrine is distilled off.The residue in the still is dissolved in 100 ml. of water and treatedwith a solution of 10 g. of sodium carbonate monohydrate in 50 ml. ofwater, whereupon the hydroxyethylated prosaniline cyanide isprecipitated as an amorphous mass. This is washed with 50 ml. of waterand air dried or dried in vacuo over sulfuric acid. The dry material islittle sensitive to radiation. It is primarilytri-p-hydroxyethyl-p-rosaniline cyanide.

Five ml. of a 1% solution of tri-fi-hydroxyethyl-prosaniline cyanide in9.1% i-propyl alcohol is added to a mixture of 10 ml. of 10% aqueousgelatine and 5 m1. of 91% i-propyl alcohol, all solutions being at 35 C.and the mixture stirred to uniformity. Water leaf paper is impregnatedby dipping and dried in the dark. It prints out a reddish violet imageon exposure to wave lengths shorter than about 3250 A.

Example 14 of one form some N Color Index No. 692

is prepared as follows: Fifty ml. of fuming sulfuric acid, 60% S0 is putin a flask equipped with a strong stirrer and a thermometer. Ten g. offinely powdered 4,4',4"- triamino-triphenyla-cetonitrile is added veryslowly to the stirred acid, the initial temperature of both reagentsbeing 25 C. Heat is evolved by the reaction, and the addition of thenitrile is controlled so that the temperature of the mixture in theflask does not rise above 60 C. When all of the nitrile has been. addedstirring is continued for /2 hour, and the mixture is then poured onto300 g. of powdered ice. The resulting solution is filtered from a littletar, boiled with activated charcoal, filtered, and the filtrateneutralized by addition of excess calcium carbonate suspended in 1 literof water. From the time of neutralization operations are carried out byyellow light, such as the illumination from a Kodak 0A safelight. Thesolution is heated to boiling, filtered from the precipitated calciumsulfate and, excess calcium carlaonate, the filtrate evaporated to avolume of 150 ml.

'acid. The yield is about 8 grams.

A solution of 0.4 g. of acid fuchsine cyanide calcium salt in 10 ml. ofwater is mixed with 20 ml. of 91% i-propyl alcohol and 12 ml. of 10%aqueous gelatine solution, all of the components being at 40 C. Glassplates are coated using 0.5 ml. of solution per square inch of surface,and dried in the dark. The colorless films print out a red, grainlessimage on exposure to ultra-violet.

Example 15 Patent blue V cyanide calcium salt having the formula VN-( rt)n s\ (C2Hb)2 Color Index No. 712

it is treated with 40 ml. of a 49% aqueous solution of sodium acetatetrihydrate, allowed to stand for 3 days and the disodium salt collectedon a filter and washed with 91% isopropyl alcohol (25 ml.) and airdried.

The free acid form is prepared by treatment of a solution of 11 g. ofthe disodium salt in ml. of water with 12.2 ml. of concentratedhydrochloric acid. After the mixture has stood at room temperature forZdays, the colorless precipitated free acid is collected on a filter,washed with water, and air dried.

The calcium salt is prepared by neutralization of a hot V2 of 1% aqueoussolution of the free acid to pH 8.4 with saturated calcium hydroxidesolution. The neutralized solution is cooled to room temperature,allowed to stand for 3 days, and filtered from the colorless,crystalline calcium salt. 7

A solution of 0.6 g. of patent blue V cyanide calcium salt in 60 ml. ofwateris mixed with 60 ml. of 10%v aqueous gelatine solution, bothsolutions being at 50 C. Glass plates are coated at 35 C., using 0.75ml. of solution per square inch of glass surface, and dried in the dark.The colorless film prints out a permanent blue image on exposure to wavelengths shorter than 3650 A.

Example 16 Malachite green cyanide iodoethylate having the formula mommotion When the solution has been saturated Il. trile) in 50 ml. ofbenzeneand 1.64 g. of ethyl iodide is placed in a tightly closedflaskand allowed to stand in the dark at' room temperature for two years. The' colorless crystals that formed during this time are collected,washed with benzene, and air dried.

Twenty-four pound water leaf paper is impregnated by dipping in a 1%aqueous solution of malachite green cyanide iodoethylate and dried inthe dark. On exposure to wave lengths shorter than about 3200 A. thepaper prints out a yellow image, which fades after a few hours storagein the dark, i. e., the paper is phototropic.

Example 17 III-H NSOaS SOaNa Colour Index No. 707, is prepared asfollows: A solution of g. of National Aniline Aniline Blue CertifiedBiological Stain brand of Soluble Blue, Colour Index No. 707, in 75 ml.of boiling water is placed in a pressure bottle with l g. of 95% sodiumcyanide, the bottle sealed and heated to 100 for 1 hour in the dark oryellow light, such as the illumination from a Kodak OA safelight. Thefollowing operations are also carried out by yellow light. Afterheating, the bottle is cooled, opened and the solution filtered from atrace of tar. The filtrate is made just acid in a good hood with 64%sulfuric acid and evaporated to dryness in vacuo at 30 C. The residue isdissolved in 50 ml. of water and shaken with 100 ml. of i propylalcohol, whereupon two layers are formed and separate on standing. Theupper alcoholic layer is decanted, the lower aqueous layer extractedwith two 20 ml. portions of i-propyl alcohol which are added to thcfirst alcoholic layer. The alcoholic extract is then evaporated todryness, leaving the salt of the dye cyanideas an amorphous glassymaterial. 7

Pure filter paper, 20 pound weight, is impregnated by dipping in a /2 of1% aqueous solution of soluble blue cyanide sodium salt, and dried inthe dark. On exposure to wavelengths shorter than about 3400 A. thepaper prints out a permanent blue image.

7 Example 18 The free acid of fast acid violet 10B cyanide having theColor Index No. 696, is prepared as follows: A solution of 25 g. ofcommercial Fast Acid Violet 10B, Colour lndex No. 696, in the form ofKiton Fast Violet 10B, manufactured by the Ciba Company, in 150 ml. ofwater heated to C. is placed in a glass pressure bottle. -To- 7.5

20 ml. of boiling 99% i-propyl alcohol.

12 the bottle is added a solution 'of 2 g. of sodium cyanide in 10 ml.of water. The bottle is sealed and heated at C. for 3 hours. T It istransferred to a dark place, allowed to cool and to stand at 25 C. for24 hours. In light from a yellow safelight, such as Kodak safelight 0A,the bottle is opened, the precipitate collected on a filter and driedwithout Washing. This precipitate'is the disodium salt.

The free acid is obtained by treating a solution of 5 g. of the disodiumsalt in 70 ml. of water at 50 C. with 6.5 ml. of 2 N hydrochloric acid.This work is carried out by yellow light. The resulting solution isallowed to stand in the dark at room temperature for 4 days, theprecipitate collected on a filter, washed with 20 ml. of cold water, anddried in the dark.

One-half gram of fast acid violet 10B cyanide free acid is dissolved bywarming to 60 C. in a mixture of 8.35 ml. of N/ 10 sodium carbonatesolution made up to 25 ml. with water. This solution is cooled to 50 C.and mixed with 50 ml. of 10% aqueous gelatin solution at the sametemperature. Twenty-five ml. of 91% i-propyl alcohol at 50 C. isimmediately added with mixing, whereupon the precipitate initiallyformed immediately redissolves. This mixture is cooled to 30 C. andcoated onto glass plates using 0.75 ml. per square inch of surface. Ondrying a clear colorless film is formed that prints out a strong,grainless, blue-violet image on exposure to ultra-violet.

Example 19 One-half gram of 4,4,4"-trihydroxy-triphenylacetonitrile,prepared by Caro and Graebe, Berichte der deutschen ChemischenGesellschaft 11, 1116, is dissolved in One g. of triethanolarnine isadded to this solution, which is cooled to 40 C. and stirred into 200ml. of a 5% aqueous suspension of low viscosity carboxymethylcellulosesodium salt (e. g. Hercules Cellulose Gum Type 70 Low). When the mixtureis homogeneous it is coated onto glass plates, using approximately 0.5ml. per square inch of surface. The plates are dried in the dark toyield uniform translucent films that print out a strong red image onexposure to ultra-violet.

Example 20 Xylene blue VS cyanide disodium salt having the formulaPI-(02115): SOaNa N-( 2 5)z QSOaNB. C

C JN

Color Index No. 672

' 13 using about 0.75 ml. per square inch of surface. The plates dry togive clear colorless films that, print out grainless cyan images onexposure to-ultra-violet. of wave lengths longer than about 3500 A.

Example 21 Xylene blue AS cyanide disodium salt having the formulaColor' Index No. 673 is prepared as described. in my copendingapplication, Serial No. 494,270, filed March 14, 1955.

One-half gram of xylene blue AS cyanide disodium salt is dissolved at 50C. in 10 ml. of water and the solution well stirred into 400 ml. of a 3%suspension of powdered karaya gum in water at 50 C. The mixture isspread on glass plates, using about 1 ml. per square inch, and dries toa rather rough translucent film which prints out a cyan image onexposure to ultra-violet of wave length shorter than 3500 A. Thispreparation prints more slowly and requires greater exposure than theprevious examples. Thus it is useful for actinometry where largerquantities of radiation are to be measured.

Example 22 Eriogaucine cyanide tripotassium salt having the formula r al r Q- $03K $62K -SO3K i ON Color Index No. 671

is prepared as follows: Twenty-five g. of Kiton pure Blue L, the CibaCompany brand of Erioglaucine, Color Index No. 671, is put in a pressurebottle with 150 ml. of boiling water. The dye dissolves immediately. Thesolution is cooled to 80 C. and a solution of 3.4 g. of 95% sodiumcyanide in' 'ml. of water is added, the bottle sealed immediately andheated for 1 hour at 100 C. The following operations are carried out byyellow light, such as the illumination from a Kodak 0A safelight.

After heating the bottle is cooled to room temperature, opened, and thesolution filtered from a trace of impurity, treated in a good 'hood with6.5 ml. of concentrated hydrochloric acid and, evaporated in vacuo atabout 50 C. to a volume of 60 ml. The acidity of the somewhat viscoussolution is adjusted with sodium hydroxide to pH 6.8. A solution of 22g. of potassium chloride in 75 ml. of boiling water is then added andthe resulting solution allowed to stand in the dark for a week withoccasional stirring and scraping of the vessel walls to accelerate thevery slow crystallization of the potassium salt. The precipitate iscollected on a filter, washed with 25 ml. of aqueous 10% potassiumchloride solution, sucked as dry as possible on the filter and dried invacuo over sulfuric acid. The yield is about g. of nearly 14 colorlessmaterial. A second crop, though containing more dye, may be obtained bythe addition of 22 g. more of potassium chloride to the mother liquor.

One-half gram of erioglaucine cyanide potassium salt, is dissolved in 20ml. of boiling Water and the solution stirred into 360 g. of a 3%aqueous sodium alginate solution at room temperature. The homogeneousSOlll tion is coated by spreading onto glass plates, using about 1 g.per square inch of surface, and dried in the dark. The resulting clear,colorless film prints out a grainless cyan image on exposure toultra-violet of wave length shorter than about 330.0 A.

In the foregoing examples, it will be understood that where notexpressly stated, the preparation of the dye cyanides and photosensitivesystems should be carried out in light from which ultra-violet has beenscreened.

I claim:

1. A solid composition comprising a combination photosensitive only toultraviolet and shorter Wave lengths consisting of a hydrocolloid and a.hydrophilic triphenylacetonitrile compound having at least one radicalselected from the group consisting of hydroxy and amino radicals at aposition para to the central methane carbon atom.

2. A solid composition comprising a combination photosensitive only toultraviolet and shorter wave lengths consisting of a hydrocolloid and ahydrophilic triphenylacetonitrile compound having at least one aminogroup at a position para to the central methane carbon atom.

3. A solid composition comprising a combination photosensitive only toultraviolet and shorter wave lengths consisting of a hydrocolloid and ahydrophilic triphenylacetonitrile compound having at least one aminogroup at a position para to the central methane carbon atom, saidcompound having in the molecule at least one radical selected from thegroup consisting of a sulfonic acid radical and its Water soluble salts.

4. The photosensitive composition of claim 3 in which said radical isattached to an aryl nucleus.

5. The photosensitive composition of claim 4 in which said aryl nucleusis attached to said central methane carbon atom.

6. The photosensitive composition of claim 4 in which said aryl nucleusis a constituent of an aralkyl radical attached to a para amino nitrogenatom.

7. A solid composition comprising a combination photosensitive only toultraviolet and shorter wave lengths consisting of a hydrocolloid and acompound selected from the group consisting of fast acid violet 10Bcyanide and its water soluble salts.

8 A solid composition comprising a combination photosensitive only toultraviolet and shorter wave lengths consisting of a hydrocolloid and acompound selected from the group consisting of Helvetia green cyanideand its water soluble salts.

9. A. solid composition comprising a combination photosensitive only toultraviolet and shorter wave lengths consisting of a hydrocolloid and acompound selected from the group consisting of acid fuchsine cyanide andits water soluble salts.

10. A solid composition comprising a combination photosensitive only toultraviolet and shorter wave lengths consisting of a hydrocolloid and ahydrophilic triphenylacetonitrile compound having at least one aminogroup at a position para to the central methane carbon atom, saidcompound having at least one hydroxyl group in the molecule.

ll. The photosensitive composition of claim 10 in which said hydroxylgroup is part of an alkanol group attached to an amino nitrogen atom.

12. The photosensitive composition of claim 11 in which said alkanolgroup is the ethanol group.

13. The photosensitive composition of claim 11 in which said alkanolgroup is a propanol group.

14. The photosensitive composition of claim 10 in 15 which said hydroxylgroupis attached to an aryl nucleus.

15. A solid composition photosensitive only to ultraviolet and shorterwave lengths, comprising a combination of a hydrocolloid and ahydroxyethylated p-rosaniline cyanide. i

16. A solid composition comprising a combination photosensitive only toultraviolet and shorter wave lengths consisting of a hydrocolloid and ahydrophilic triphenylacetonitrile compound having at least one aminogroup at a position para to the central methane carbon atom, saidcompound having at least one quaternary ammonium group represented bythe formula in which R, R and R are each an alkyl group and X isananion.a

17. A solid composition comprising a combination photosensitive only toultraviolet and shorter Wave lengths consisting of a hydrocolloid andethyl green cyanide.

18. A product of manufacture comprising a base sheet coated with a solidcomposition, said composition comprising a combination photosensitiveonly to ultraviolet and shorter Wave lengths consisting of ahydrocolloid and a hydrophilic triphenylacetonitrile compound having atleast one radical selected from the group consisting of hydroxy andamino radicals at a position para to the central methane carbon atom.

19. A product of manufacture comprising a base sheet coated with a solidcomposition, said composition comprising a combination photosensitiveonly to ultraviolet and shorter Wave lengths consisting of ahydrocolloid and a hydrophilic triphenylacetonitrile compound having atleast one amino group at a position para to the central methane carbonatom, said compound having in the molecule at least one radical selectedfromthe group consisting of a sulfonic acid radical and its watersoluble salts.

20. A product of manufacture comprising a base sheet coated with a solidcomposition, said composition comprising a combination photosensitiveonly to ultraviolet and shorter wave lengths consisting of ahydrocolloid and a hydrophilic triphenylacetonitrilecompound having atleast one amino group at a position para to the central methane carbonatom, said compound having at least one hydroxyl group in the molecule.

21. A product of manufacture comprising a base sheet coated with a solidcomposition, saidcomposition comprising a combination photosensitiveonly to ultraviolet and shorter Wave lengths consisting of ahydrocolloid and a hydrophilic triphenylacetonitrile compound having atleast one amino group at a position para to the central methane carbonatom, said compound having at least one quaternary ammonium grouprepresented by the formula -1 IR 1I1 R1 in which R, R and R are each analkyl group and X is an anion.

22. A photochemical process comprising exposing to ultra-violet light toproduce a colored compound, a solid composition including a combinationphotosensitive only to ultraviolet and shorter wave lengths consistingof a hydrocolloid and a hydrophilic triphenylacetonitrile com- 16 poundhaving at least one radical selected from the group consisting ofhydroxy and amino radicals at a position para to the central methanecarbon atom.

23. A photochemical process comprising exposing to ultra-violet light toproduce a colored compound, a solid composition including a combinationphotosensitive only to ultraviolet and shorter wave lengths consistingof a hydrocolloid and a hydrophilic triphenylacetonitrile compoundhaving at least one amino group at a position para to the centralmethane carbon atom, said compound having in the molecule at least oneradical selected from the group consisting of a sulfonic acid radicaland its water soluble salts.

24. A photochemical process comprising exposing to ultraviolet light toproduce a colored compound, a solid composition including a combinationphotosensitive only to ultraviolet and shorter wave lengths consistingof a hydrocolloid and a hydrophilic triphenylacetonitrile compoundhaving at least one amino group at a position para to the centralmethane carbon atom, said compound having at least one hydroxy group inthe molecule.

25. A photochemical process comprising exposing to ultra-violet light toproduce a colored compound, a solid composition including a combinationphotosensitive only to ultraviolet and shorter wave lengths consistingof a hydrocolloid and a hydrophilic triphenylacetonitrile compoundhaving at least one amino group at a position para to the centralmethane carbon atom, said compound having at least one quaternaryammonium group represented by the formula R2 Rl in which R, R and R areeach an alkyl group and X is an anion.

26. A solid composition comprising a combination photosensitive only toultraviolet and shorter wave lengths consisting of a hydrocolloid and ahydrophilic triphenylacetonitrile compound having at least one hydroxygroup at a position para to the central methane carbon atom.

27. A solid composition comprising a combination photosensitive only toultraviolet and shorter wave lengths consisting of a hydrocolloid and acompound selected from the group consisting of soluble blue cyanide andits Water-soluble salts.

28. A solid composition comprising a combination photosensitive only toultraviolet and shorter Wave lengths consisting of a hydrocolloid and acompound selected from the group consisting of patent blue V cyanide andits water-soluble salts.

References Cited in the file of this patent UNITED STATES PATENTS412,614 Hermann October 1889 2,150,695 Muehler Mar. 14, 1939 2,366,179Chalkley Jan. 2, 1945 2,441,561 Chalkley May 18, 1949 2,528,496 ChalkleyNov. 7, 1950 OTHER REFERENCES Color Index, 1st ed., January 1924, pub.Society of Dyers and Colourists, Bradford, Yorkshire, Numbers 0 660, 692and 696.

1. A SOLID COMPOSITION COMPRISING A COMBINATION PHOTOSENSITIVE ONLY TOULTRAVIOLET AND SHORTER WAVE LENGTHS CONSISTING OF A HYDROCOLLOID AND AHYDROPHILIC TRIPHENYLACETONITRILE COMPOUND HAVING AT LEAST ONE RADICALSELECTED FROM THE GROUP CONSISTING OF HYDROXY AND AMINO RADICALS AT APOSITION PARA TO THE CENTRAL METHANE CARBON ATOM.